Como Diminuir uma foto automaticamente?

public static Image resizeImage(Image im, int with)
    {

        double proporcao = with / (double) im.getWidth(null);
        int newHeigth = (int)(im.getHeight(null) * proporcao);

        BufferedImage bum = new BufferedImage(with, newHeigth, BufferedImage.TYPE_INT_ARGB);

        Graphics2D graf = bum.createGraphics();

        graf.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BILINEAR);
        graf.drawImage(im, 0,0, with, newHeigth, null);
        graf.dispose();

        return bum;
    }